The advantage of the double-faced knitting is that it can combine, in the same structure, the characteristics of each of the two faces, which are selected as a function of the requirements linked to the use to be made of the final garment. For example, if the garment is designed to be in contact with the wearer's skin, then it should be soft to the touch. In the case of leisure wear, the inside face should have perspiration-absorbing properties, and the outside face should ensure a good thermal insulation.
Double-faced knitted fabrics have already been proposed, of which the surface of each face is in a different material. For example, in documents DE-2 530 806 and DE-3 409 965, the outside face is in wool while the inside face, which is in contact with the wearer is respectively in cotton for DE-2 530 806 and in silk for DE-b 3 409 965.
A number of knitting techniques have already been proposed for producing the double-faced knitting. The first one consists in a knitting of plaited jersey type in which a single-knit knitting machine is fed with two yarns of different material; in this case, the two yarns must be quite separate and presented to the needles such that one is always placed on the wrong side and the other on the right side. This first technique requires a very accurate control of the yarns-feeding members; the resulting knitting is not thick and not sufficiently extensible. A thicker knitting can be obtained according to a variant of this first technique, by producing on a conventional rib knitting machine a double-faced plaited knitting.
According to the second technique, the double-faced knitting is produced on three feeds: the first two feeds being formed of two quite separate layers of stocking stitch, and the third being a linking yarn of very low count, generally a synthetic filament which, by curling, interlocks the two other layers. This second technique is very easy to use but it has the disadvantage of requiring the presence of a linking yarn which is made of a third material, and it feels like two juxtaposed knittings.
The third technique is the resultant from the second in that interlocking of the two layers is achieved by one of the two components. Using this technique with a circular knitting machine, the knitting is obtained from two feeds: in one is the yarn of the first material and all the needles on the dial are working, and in the other is the yarn of the second material and all the needles of the cylinder are working; the two layers are interlocked either by Iooping the yarn of the first material on the needles of the cylinder or by looping the yarn of the second material on the needles of the dial. The formation of the layers in either one of the two main components makes the structure of the stitch rather unstable. The knitting is extensible enough but its elasticity is poor and at the finishing stage, the dimensional stability obtained is often inadequate.